Since the advent of the computer graphical user interface (GUI), there has been a need for a user-manipulable pointing device, used in addition to a keyboard, for allowing a user to enter input commands to move a cursor around a displayed desktop. A mouse has been the most common such device. Use of a mouse has generally required a flat working surface, so that the mouse can be slid over the surface. A mouse has been an impractical accessory for portable computers, because it must be carried separately, and because the required flat surface is not always available to the traveling user.
The advancing state of the art in component miniaturization has made possible lightweight, portable "laptop" computers. Such computers generally are about the size and dimensions of a book. They have a "clamshell" structure, in which they open by folding upward a hinged first half, substantially completely taken up on the inside by an LCD display, and a second, base, half which is mainly taken up on the inside by a keyboard. System components such as a battery, a hard disk drive, etc., are designed to be compact ad flat, so as, in most cases, to fit underneath the keyboard in the base half.
Of course, portability of a laptop computer requires that other necessary components, such as a detached mouse, an AC power cord and adapter, etc., be as compact as possible. Any such additional component detracts from the convenience and compactness of the laptop system.
Convenience and portability made a quantum leap forward with the advent of IBM Corporation's TrackPoint II.RTM. and TrackPoint III.RTM. devices (hereinafter referred to generically as "TrackPoint devices"). A TrackPoint device is a small structure, preferably resembling the eraser end of a pencil, strategically positioned in the middle of the keys of a keyboard. The user, whose hands are already in the vicinity of the TrackPoint device by virtue of being on the keys of the keyboard, manipulates the TrackPoint device with a fingertip. Signals are produced, which are processed in a manner similar to mouse signals. Responsive to the signals, the computer moves the cursor around the display in accordance with the user's fingertip manipulation.
TrackPoint devices are preferably implemented as described in co-pending, co-assigned patent application Ser. No. 08/181,648 (filed Jan. 14, 1994) and (IBM docket number AM9-96-049, serial number to be determined) (filed Oct. 23, 1996). These physical implementations essentially include a vertically oriented member, projecting slightly above the level of the keys, and a fingertip contact member, such as that described in co-pending patent application Ser. No. 08/315,651 (filed Sep. 30, 1994).
The TrackPoint device has greatly added to the user's convenience, both because it is easy to use, and also it need not be carried separately. It is small, and fits inside the laptop computer. As far as the user transporting the computer is concerned, it is as though no additional user interface device is needed at all.
However, because the TrackPoint device projects above the plane of the key surfaces, it has limited realization of the goal of making laptop computers as small and compact as possible. The problem has been that, when the lid of the computer is closed, the upper surface of the grippy top may come into direct contact with the display surface. This contact results in undesirable smearing, or even abrasion, of the display surface.
Even more serious is a problem caused when a user carries a laptop in a way that the sides of the laptop get squeezed. This can happen when the laptop is put into a briefcase along with other materials, and the briefcase is closed. If (as is all to often the case) the briefcase is overloaded, the laptop is squeezed in a way that forces the TrackPoint device against the display. This forcing can not only damage the display surface, but also damage the inner workings of displays such as liquid crystal displays (LCDs).
Therefore, there is a need for a further refinement of the structure of TrackPoint-type in-keyboard pointing devices, so that laptop displays are not damaged, and so that further reductions in the dimensions of laptops are not impeded.